Quitting smoking. Losing weight. Getting toned. While most New Year’s resolutions are admirable, they’re often heavy on self-involvement. By turning the focus outward and concentrating on giving back in 2013, you can help others while you help yourself. A wealth of studies show that philanthropy in its many forms — reading to children, volunteering at a soup kitchen, cleaning up your neighborhood, taking part in AIDS walks — can yield dramatic physical results for the giver. Here’s what you can expect if you embrace altruism in the coming year.